Is home genetic testing a good idea?

How will you use the information?

With a drop of spit and a couple hundred bucks, you can learn a lot about your genetic ancestry and your risk for developing certain diseases.

Sort of.

Although I’d accept without question a report that told me which continent my ancestors hailed from, I’d be much less willing to make decisions about my health based on one of these home genetic testing kits.

Why? Isn’t all information good?

Only if you know what to do with it after you have it.

Dr. Harriet Hall over at Science-Based Medicine points out a couple of the problems with these direct-to-consumer genetic tests.

One, people don’t change their behaviors.

[An] expected benefit of genomic testing is that if people knew they were at high risk of a disease, they would take preventive steps to reduce their risk. That seems plausible; but a recent study, a systematic review in theBMJ (formerly theBritish Medical Journal) calls that assumption into question. It found that communicating DNA-based disease risk estimates did not increase risk-reducing health behaviors or motivation to engage in such behaviors.

I would suggest the opposite, as well. If my genetic report told me I had a less-than-average risk of developing melanoma, I wouldn’t suddenly start using a tanning bed or forgoing sunscreen. I would continue to take prudent steps to prevent skin cancer and premature aging. That’s just what I do.

Two, genetic testing is not a diagnosis; it does not predict with 100% accuracy whether you will or won’t get a disease, only the relative likelihood. The test can’t account for all genetic, environmental and lifestyle variables.

Many diseases are multifactorial. The expression of one gene may be affected by other genes and by environmental and lifestyle factors. Having a gene associated with a disease does not mean you will get that disease; the most it might do is increase the probability. And conversely, having variants associated with low risk is no guarantee that you won’t get the disease. And the different companies don’t even agree with each other.

Will it save you money?

Probably not.

One argument in favor of home genetic testing is that knowing your risk for different diseases can save you money. Considering the cost of healthcare these days, isn’t that worth an investment of $199?

Well, some of the information I can get for free, just by knowing my family history. I don’t need to pay $199 to find out I’m at increased risk of developing diabetes, because my mom, several maternal aunts and my maternal grandmother all had Type-2 diabetes.

Talk to your family members. Is there a history of heart disease, stroke, diabetes or certain cancers? Diseases that affect several generations or strike at a younger age, such as a heart attack or breast cancer at age 40, are usually associated with an increased genetic risk.

If your results worry you, you could schedule a longer visit with your physician or a geneticist—at your expense—who will likely order more diagnostic tests or schedule more frequent visits. You could end up spending much more than you save.

Will it give you peace of mind?

Probably not.

I think what bothers me the most about these home test kits is that they don’t provide any counseling, either before or after.

Why do you want the test? What are you looking for? What will you do with the information? Will the results change your behavior? How comfortable (or not) are you with knowing your risk of certain diseases?

One of the most popular home genetic testing companies, 23andMe,recently obtained FDA approval to assess and report genetic risk for several diseases: Alzheimer’s disease, Parkinson’s, celiac disease (for glucose intolerance), and several other blood and clotting disorders.

How would knowing I or my husband was at increased risk of Alzheimer’s help us? We already do what we can to delay or prevent dementia through a healthy lifestyle. There is nothing we would be able to do but worry. A lot. The same with Parkinson’s or multiple sclerosis.

In fact, 23andMe includes a disclaimer with its results that people with depression or anxiety might want to think again before finding out if they are at risk of developing one of these incurable diseases.

Bottom line: I wouldn’t spend my money on one of these home genetic testing kits because 1) it wouldn’t change my behavior; 2) it probably wouldn’t give me any useful information that I didn’t already know from my family history; and 3) it would cause me anxiety to find out I had an increased risk of developing a horrible disease that I couldn’t do anything about.

Someone else might have a totally different reaction. There are lots of “quantitative self” types out there who want to know EVERYTHING.

That’s fine. My only point is to know before you buy.

Think through what you want to get from this type of genetic testing, know its limitations, and then have a plan for what you will do with the information—good or bad—after you get it.